McGee-Stafford went 8 for 11 from the field and made all four of her free throws for the Longhorns (22-11), who shot 61 percent in the second half to end a skid of four consecutive first-round losses.

Next up for the Longhorns is fourth-seeded Maryland, which beat Army.

Alyssa Baron scored 25 points to lead the Quakers (23-6), who were trying to become only the second Ivy League team to win a game in the women's tournament. The conference dropped to 1-22 all-time, although the one win was historic: Harvard over Stanford in 1997, the only victory by a No. 16 seed over a No. 1 in men's or women's tournament history.

Texas trailed 32-17 late in the first half and 38-31 at halftime, but the stronger, more athletic Longhorns cut down on their turnovers and took advantage of Penn's foul trouble to pull off a 22-2 run early in the second half. Meanwhile, Ivy League rookie and defensive player of the year Sydney Stipanovich picked up her fourth foul soon after halftime, and Kara Bonenberger fouled out for the Quakers with 7:03 to play.

Stipanovich, the niece of former Indiana Pacers center Steve Stipanovich, finished with 14 points, most of them coming when Penn was trying to make up a double-digit deficit late in the game.

The Longhorns were careless early on, committing turnovers on five consecutive possessions during a 9-0 run by Penn. Baron accounting for seven of the points with a give-and-go layup, a short jumper after an offensive rebound, and a 3-pointer.

The spurt was part of an overall 18-2 run when Texas went nearly 10 minutes without a field goal, missing eight straight shots. Baron added an off-balance layup, and her free throw with 4:35 remaining gave the Quakers a 15-point lead.

The Longhorns finally regrouped and put together an 8-0 run, including a three-point play by GiGi Mazionyte that drew a third foul on Stipanovich.

Baron had 18 points at the break, and the Quakers had committed only three turnovers to Texas' 12. But, after Stipanovich picked up her fourth foul with 16:58 to play, Penn had no answer inside for McGee-Stafford.

Chassidy Fussell gave Texas its first lead since early in the game with a 3-pointer that made it 44-43 with 14½ minutes left, part of a 14-0 run that turned an eight-point deficit into a six-point lead. McGee-Stafford's three-point play with 10:27 remaining gave the Longhorns a double-digit lead, and they weren't seriously threatened the rest of the way.